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QFS LS Swap Fuel Line Kit for 1973-1991 Chevy & GMC Square Body Pickups - Automotive Performance, HFP-FSYS4 | QFS

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LS Swap Fuel Line Kit for 1973-1991 Chevy & GMC Square Body Pickups - Automotive Performance, HFP-FSYS4 | QFS

$384.98
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SKU:
HFP-FSYS4-BC
MPN:
HFP-FSYS4
UPC:
840477712910
Availability:
Current Lead Time: 3-5 Days
Weight:
5.00 LBS

  • SIGNIFICANT
    SAVINGS

  • EASY
    INSTALLATION

  • COMPREHENSIVE
    SUPPORT

HFP-FSYS4 is a streamlined, high-performance fuel line kit for LS and LT engine swaps in 1973–1991 Chevrolet and GMC square body trucks. Designed to support modern fuel injection systems, HFP-FSYS4 includes premium Phenix AN fuel hoses, Quantum billet fittings, and a combined fuel filter/regulator calibrated to 58 PSI—ideal for LS and LT engines.

This kit simplifies your fuel system upgrade without overcomplicating your build. Perfect for budget-conscious or DIY installers, HFP-FSYS4 delivers everything needed to ensure proper fuel pressure and flow, without the added components of a full system like HFP-FSYS5. It’s an ideal match for any pump offered with Quantum’s square body AN fuel pump hangers.

 

Compatible with all 1973–1991 GM square body pickup submodels, including:
C10, C20, C30, K10, K20, K30,
R10, R1500, R20, R2500, R30, R3500,
V10, V20, V30, V3500

Pair with the QFS-H880 fuel pump hanger for a complete and dependable fuel delivery system tailored to your LS swap project.

 

Package Includes:

  • (1) 64 in. Black Nylon Double Braided Stainless E85 Hose w/ -06 Straight Fittings
  • (2) 24 in. Black Nylon Double Braided Stainless E85 Hose w/ -06 Straight Fitting & -06 45° Fitting
  • (1) 58 psi Fuel Pressure Regulator/Filter w/ (1) 5/16 fitting & (2) 3/8 fitting
  • (1) Fuel Rail Fitting
 

PLEASE NOTE:

  • Not suitable for 1990s era LT1.
  • Not recommended for dual pump setups.
  • Not suitable for turbo or supercharged applications, which require vacuum reference.
 

WARNING

This product can expose you to chemicals which are known to the State of California to cause cancer and birth defects or other reproductive harm.  For more information go to  www.P65Warnings.ca.gov.

Brand Name:
Quantum
There is a one-year limited warranty on this product. This warranty only applies to the original customer and is non-transferable. Improper use or installation of the product voids this warranty, and Quantum is not responsible for incidental costs resulting from the failure of the product. Please contact our technical support directly prior to making a warranty request.

HFP-FSYS4 LS Swap Fuel Line Kit for 1973-1991 Chevy and GMC Square Body Pickups

The HFP-FSYS4 is a streamlined high-performance fuel line kit engineered for LS and LT engine swaps in 1973 to 1991 Chevrolet and GMC Square Body pickups. Modern fuel injection demands proper line sizing, pressure regulation, and clean filtration, and this kit delivers all three components in one straightforward package built for swap builders.

Purpose-Built for 1973 to 1991 GM Square Body Trucks

Purpose-Built for 1973 to 1991 GM Square Body Trucks

The HFP-FSYS4 is compatible with all 1973 to 1991 GM Square Body pickup submodels, covering the C10, C20, C30, K10, K20, K30, R10, R1500, R20, R2500, R30, R3500, V10, V20, V30, and V3500. That broad fitment makes it a flexible solution across two-wheel-drive, four-wheel-drive, and heavy-duty Square Body platforms.

Combined Fuel Filter and Regulator Calibrated to 58 PSI

Combined Fuel Filter and Regulator Calibrated to 58 PSI

LS and LT engines require steady fuel pressure to fire correctly under load. The HFP-FSYS4 includes a combined fuel filter and pressure regulator calibrated to 58 PSI, the standard Corvette LS pressure spec. That dialed-in setpoint delivers consistent fueling at idle and full throttle, preventing the lean spikes that lead to drivability complaints.

Complete Kit With Phenix AN Hoses and Quantum Billet Fittings

Complete Kit With Phenix AN Hoses and Quantum Billet Fittings

The HFP-FSYS4 ships with one 64-inch and two 24-inch Black Nylon Double Braided Stainless E85 hoses, premium Quantum billet fittings, the 58 PSI filter and regulator with included fittings, and a fuel rail fitting. Every component required to plumb the engine bay is included, eliminating the need to source parts piecemeal.

A Streamlined Fuel Line Solution for Square Body LS and LT Swaps

Square Body LS swaps live or die by their fuel system. The HFP-FSYS4 simplifies that build without overcomplicating it, providing a high-quality fuel line kit suited for budget-conscious and DIY installers who want proven hardware. It pairs cleanly with Quantum's Square Body fuel pump hangers for a complete fuel delivery setup.

Compatible With E85 and Modern Ethanol-Blended Fuels

Compatible With E85 and Modern Ethanol-Blended Fuels

Every hose in the HFP-FSYS4 is constructed from black nylon double-braided stainless E85 line, engineered to handle modern ethanol-infused pump gasoline and dedicated E85 fuel. Flex fuel tunes are common in LS builds, and this kit holds up to that chemistry without the breakdown that affects standard rubber fuel hose over time.

Designed to Pair With Quantum Square Body Fuel Pump Hangers

Designed to Pair With Quantum Square Body Fuel Pump Hangers

The HFP-FSYS4 is engineered to match any pump offered with Quantum's Square Body AN fuel pump hangers, including the QFS-H880. Pairing the two creates a complete and dependable fuel delivery system tailored to the LS or LT swap, eliminating compatibility guesswork and providing a properly sized supply line from tank to rail.

American-owned with QFS Customer Support

American-owned with QFS Customer Support

Quantum Fuel Systems is American-owned and based in Ventura, California, with US-based technical support staff available to assist with sizing, fitment, and installation questions throughout the build. A one-year limited warranty backs the HFP-FSYS4 against defects in materials or workmanship for the original purchaser.

Frequently Asked Questions

The HFP-FSYS4 delivers fuel from the in-tank pump to the engine's fuel rail at the regulated pressure required by LS and LT engines. It combines AN hoses, billet fittings, and a 58 PSI filter and regulator into a single kit that plumbs the high-pressure side of an LS swap fuel system.

The HFP-FSYS4 is compatible with all 1973 to 1991 GM Square Body pickup submodels, including C10, C20, C30, K10, K20, K30, R10, R1500, R20, R2500, R30, R3500, V10, V20, V30, and V3500. Compatibility is confirmed for LS and LT engine swap applications using single in-tank pump configurations.

The kit includes one 64-inch and two 24-inch Black Nylon Double Braided Stainless E85 hoses with -06 fittings, a 58 PSI fuel pressure regulator and filter with one 5/16 fitting and two 3/8 fittings, and one fuel rail fitting. Every component required to plumb the high-pressure side is included.

The HFP-FSYS4 is not suitable for 1990s-era LT1 engines, dual pump fuel system setups, or turbocharged and supercharged applications that require a vacuum-referenced regulator. Builds running forced induction need a regulator with a boost reference port to maintain proper rail pressure under positive manifold pressure conditions.

Yes. Every hose in the HFP-FSYS4 is constructed from E85-rated black nylon double-braided stainless line, fully compatible with modern ethanol-infused pump gasoline and dedicated E85. Flex fuel tunes are common in LS swap builds, and this kit is engineered to handle the chemistry without degradation over the lifespan of the system.

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